Memory device that performs erase operation to preserve data reliability

ABSTRACT

A memory device may include a memory block and a control circuit. The memory block may include a first sub-block and a second sub-block that are connected between a common source line and a plurality of bit lines and may be vertically stacked. The control circuit may be configured to select any one of the common source line and the plurality of bit lines as a transmission path of an erase voltage based on positions of the first sub-block and the second sub-block, and perform erase operations on the first sub-block and the second sub-block in units of sub-blocks.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2020-0181181, filed on Dec. 22,2020, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated by reference herein in its entirety.

BACKGROUND

The present disclosure relates to a memory device, and moreparticularly, to a memory device including a three-dimensional memorycell array for performing an erase operation in a sub-block unit.

Research has been conducted into a semiconductor memory device having athree-dimensional array structure to improve an integration degree of asemiconductor memory device, and technology for performing a memoryoperation in a sub-block unit is suggested to effectively manage memoryblocks that are greater than those in an existing two-dimensional arraystructure. Recently, semiconductor memory devices for supporting apartial erase operation of performing an erase operation in a sub-blockunit has been suggested.

Boosting channels of sub-blocks that are erase targets with an erasevoltage may be interrupted by other sub-blocks, and furthermore, datastored in other sub-blocks may deteriorate because of the erase voltage,which causes the degradation in the data reliability.

SUMMARY

The present disclosure provides a memory device having athree-dimensional memory cell array and a memory device capable ofsecuring the data reliability by performing an effective erase operationbased on positions of sub-blocks.

According to an aspect of the inventive concept, there is provided amemory device including a memory block including a first sub-block and asecond sub-block that are connected between a common source line and aplurality of bit lines and vertically stacked, and a control circuitconfigured to select any one of the common source line and the pluralityof bit lines as a transmission path of an erase voltage based onpositions of the first sub-block and the second sub-block, and performerase operations on the first sub-block and the second sub-block inunits of sub-blocks.

According to another aspect of the inventive concept, there is provideda memory device including a lower chip including a peripheral circuitregion, and a first upper chip stacked on the lower chip, connected tothe lower chip according to a bonding method, and including a first cellregion, wherein the first cell region includes: a first metal layerformed adjacent to the lower chip and connected to a plurality of firstbit lines; a first substrate formed at a higher level than the firstmetal layer and having a lower surface on which a first common sourceline is formed; and at least two first sub-blocks connected between theplurality of first bit lines and the first common source line andvertically stacked, and the peripheral circuit region includes a controlcircuit configured to select any one of the plurality of first bit linesand the first common source line as a transmission path of an erasevoltage based on positions of the at least two first sub-blocks, andperform an erase operation on the at least two first sub-blocks.

According to another aspect of the inventive concept, there is provideda memory device including a lower chip including a peripheral circuitregion, and a first upper chip stacked on the lower chip, connected tothe lower chip according to a bonding method, and including a first cellregion, a second upper chip stacked on the first upper chip, connectedto the first upper chip according to the bonding method, and including asecond cell region, wherein the first cell region includes: a firstsubstrate adjacent to the second upper chip and having a lower surfaceon which a first common source line is formed; a first metal layeradjacent to the lower chip and connected to the plurality of first bitlines; and a first sub-block including a plurality of first memory cellsvertically stacked, the second cell region includes: a second substratehaving a lower surface on which a second common source line is formed; asecond metal layer adjacent to the first upper chip and connected to aplurality of second bit lines; and a second sub-block including aplurality of second memory cells vertically stacked, and a direction, inwhich a channel of the first sub-block is boosted by the erase voltageduring an erase operation on the first sub-block, is different from adirection, in which a channel of the second sub-block is boosted by theerase voltage during an erase operation on the second sub-block.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will be more clearly understoodfrom the following detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a block diagram of a memory device according to an exampleembodiment;

FIG. 2A is a diagram of a memory cell array of FIG. 1 ; FIGS. 2B and 2Care diagrams for explaining a configuration of one of memory blocks ofFIG. 2A; FIG. 2D is a diagram for explaining a memory device having aCOP structure, according to example embodiments;

FIG. 3 is a circuit diagram of the memory block of FIG. 2B;

FIG. 4 is a flowchart of an operation method of a memory device,according to an example embodiment;

FIG. 5 is a diagram of a cell string included in a memory block,according to an example embodiment;

FIGS. 6A and 6B are diagrams for explaining an erase operation performedon a first sub-block in the cell string of FIG. 5 according to exampleembodiments;

FIGS. 7A and 7B are diagrams for explaining an erase operation performedon a second sub-block in the cell string of FIG. 5 according to exampleembodiments;

FIGS. 8A and 8B are diagrams for explaining the erase operationperformed on a second sub-block in the cell string of FIG. 5 accordingto example embodiments;

FIGS. 9A to 9C are diagrams of examples of sub-blocks included in amemory block on which an erase operation is performed, according to anexample embodiment;

FIG. 10 is a flowchart of an operation method of a memory device,according to an example embodiment;

FIGS. 11A and 11B are diagrams for explaining an erase method of asecond sub-block, according to example embodiments;

FIG. 12 is a flowchart of an operation method of a memory system,according to an example embodiment;

FIG. 13 is a block diagram of a Solid State Drive (SSD) system accordingto an example embodiment;

FIG. 14 is a cross-sectional view for explaining a memory device as anexample of the memory device of FIG. 1 according to example embodiments;and

FIGS. 15A to 15D are cross-sectional views of memory devices each havinga Chip to Chip (C2C) structure as examples of the memory device of FIG.1 according to example embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, one or more embodiments of the present disclosure will bedescribed in detail with reference to the attached drawings.

Hereinafter, one or more embodiments of the present disclosure may bedescribed by referencing a NAND flash memory. However, the spirit of theinventive concept is not limited to the NAND flash memory. The spirit ofthe inventive concept may be applied to various non-volatile memorydevices such as Electrically Erasable and Programmable ROM (EEPROM), aNOR flash memory device, Phase-change RAM (PRAM), Magnetic RAM (MRAM),Resistive RAM (RRAM), and Ferroelectric RAM (FRAM).

FIG. 1 is a block diagram of a memory device 100 according to an exampleembodiment.

Referring to FIG. 1 , the memory device 100 may include a memory cellarray 110, a page buffer circuit 120, a control logic 130, a voltagegenerator 140, a row decoder 150, and a data input/output circuit 160.Hereinafter, the control logic 130 may be referred to as a controlcircuit. The control logic 130 may include an erase control module 132for controlling an erase operation, according to example embodimentsdescribed below. Although not illustrated in FIG. 1 , the memory device100 may further include various functional blocks related to a memoryoperation. The erase control module 132 may be realized as a hardwarelogic, a software logic, or a hardware/software compound logic. Theerase control module 132 may also be realized as one or more logiccircuits.

The memory cell array 110 may include cell strings (or strings) arrangedon a substrate in row and column directions. Each cell string mayinclude memory cells stacked in a direction perpendicular to thesubstrate. That is, the memory cells may be stacked in the directionperpendicular to the substrate and form a three-dimensional structure.Each memory cell may be, for example, a single-level cell, a multi-levelcell, a triple-level cell, a quadruple-level cell, or the like. Thespirit of the inventive concept may be flexibly applied to various celltypes of the memory cells. One memory block of the memory cell array 110may include a first sub-block SB1 and a second sub-block SB2.Hereinafter, a sub-block may be a memory unit in which memory cellsincluded in a memory block are logically or physically divided, and maybe defined as a certain unit in which a partial erase operation isavailable in the memory block. The control logic 130 may operate thefirst sub-block SB1 and the second sub-block SB2 in one memory block.

In an example embodiment, cell types of the first sub-block SB1 and thesecond sub-block SB2 may be identical to or different from each other.Also, the number of memory cells included in the first sub-block SB1 maybe identical to or different from the number of memory cells included inthe second sub-block SB2. In some embodiments, the number of word linesconnected to the first sub-block SB1 may be identical to or differentfrom the number of memory cells included in the second sub-block SB2.

The memory cells of the memory cell array 110 may be connected to therow decoder 150 through word lines WL, string selection lines SSL,ground selection lines GSL, bit lines BL, a first Gate Induced DrainLeakage (GIDL) selection line GIDL_SL1, and a second GIDL selection lineGIDL_SL2 and may be connected to the page buffer circuit 120 through thebit lines BL. Voltages having controlled levels may be applied to thefirst GIDL selection line GIDL_SL1 and the second GIDL selection lineGIDL_SL2 so that an operation according to example embodiments may beperformed during the erase operation. Voltages having fixed levels maybe applied during operations other than the erase operation.

The page buffer circuit 120 may temporarily store data to be programmedin the memory cell array 110 and data that is read from the memory cellarray 110. The page buffer circuit 120 may include page buffers (orlatches). For example, each page buffer may include latches respectivelycorresponding to the bit lines BL and may store data in a page unit. Thepage buffer circuit 120 may include a sensing latch, and the sensinglatch may include sensing latches respectively corresponding to the bitlines BL. Also, each sensing latch may be connected to a sensing node atwhich data is detected through a corresponding bit line.

The control logic 130 may control all operations of the memory device100. For example, the control logic 130 may program data in the memorycell array 110 based on a command CMD, an address ADDR, and a controlsignal CTRL received from a memory controller (not illustrated), mayread the data from the memory cell array 110, or may output variousinternal control signals for erasing the data stored in the memory cellarray 110.

The internal control signals output from the control logic 130 may beprovided to the page buffer circuit 120, the voltage generator 140, andthe row decoder 150. In detail, the control logic 130 may provide avoltage control signal CS_vol to the voltage generator 140. The voltagegenerator 140 may include one or more pumps (not illustrated) and maygenerate voltages VWL having different levels according to a pumpingoperation according to the voltage control signal CS_vol. Also, thecontrol logic 130 may provide a row address X_ADD to the row decoder 150and a column address Y_ADD to the page buffer circuit 120. Hereinafter,an operation of the erase control module 132 is described, and thecontrol logic 130 may generate internal control signals regarding theoperation of the erase control module 132 and output the internalcontrol signals to functional blocks of the memory device 100,respectively. Also, the operation of the erase control module 132 may bedefined as an operation of the control logic 130.

In an example embodiment, the erase control module 132 may select anyone of the bit lines BL and a common source line (not illustrated) as atransmission path of an erase voltage, based on positions of the firstand second sub-blocks SB1 and SB2, and the erase control module 132 mayperform the erase operations on the first and second sub-blocks SB1 andSB2 in sub-block units. Hereinafter, for better understanding, it isassumed that the second sub-block SB2 is stacked on the first sub-blockSB1 and thus is closer to the bit lines BL than the first sub-block SB1.

In an example embodiment, the erase control module 132 may select thecommon source line (not illustrated) as a transmission path of the erasevoltage during the erase operation. Accordingly, because of the erasevoltage applied through the common source line (not illustrated),channels of the first sub-block SB1 and the second sub-block SB2 may besequentially boosted.

In an example embodiment, the erase control module 132 may select thebit lines BL as transmission paths of the erase voltage, during theerase operation performed on the second sub-block SB2. Accordingly,because of the erase voltage applied through the bit lines BL, thechannels of the second sub-block SB2 and the first sub-block SB1 may besequentially boosted.

In some embodiments, the erase control module 132 may select all of thecommon source line (not illustrated) and the bit lines BL as thetransmission paths of the erase voltage, during the erase operationperformed on at least one of the first sub-block SB1 and the secondsub-block SB2. Accordingly, because of the erase voltage applied throughthe bit lines BL and the common source line (not illustrated), thechannels of the first sub-block SB1 and the second sub-block SB2 may beboosted.

As described above, the erase control module 132 may variously selectthe transmission paths of the erase voltage according to whether aposition of a target sub-block that is an erase target, that is, whetherthe target sub-block is adjacent to the common source line (notillustrated) or the bit line BL.

However, the illustration of FIG. 1 is merely an example, and one ormore embodiments are not limited thereto. The memory cell array 110 mayinclude more sub-blocks in addition to the first sub-block SB1 and thesecond sub-block SB2, and the erase control module 132 may select thetransmission path of the erase voltage based on the positions of thesub-blocks and perform the erase operations in the sub-block units.

In an example embodiment, the memory device 100 may have any one ofstack structures, a Cell Over Periphery (COP) structure, and a bondingstructure, and erase methods according to example embodiments may beapplied to sub-blocks included in respective embodiments. The embodimentregarding the stack structures will be described in detail withreference to FIG. 2C, the embodiment regarding the COP structure will bedescribed in detail with reference to FIG. 2D, and the embodimentregarding the bonding structure will be described in detail withreference to FIGS. 14 and 15A to 15D.

FIG. 2A is a diagram of a memory cell array 110 of FIG. 1 , FIGS. 2B and2C are diagrams for explaining a configuration of one of memory blocksof FIG. 2A, and FIG. 2D is a diagram for explaining a memory devicehaving a COP structure, according to example embodiments.

Referring to FIGS. 1 and 2A, the memory cell array 110 may includememory blocks BLK1 to BLKz (z is a natural number greater than 1). Thememory blocks BLK1 to BLKz may each have a three-dimensional structure(a vertical structure). For example, each of the memory blocks BLK1 toBLKz may include structures extending in first to third directions. Eachof the memory blocks BLK1 to BLKz may include cell strings (notillustrated) extending in the second direction. The cell strings (notillustrated) may be apart from each other in the first and thirddirections. The cell strings (not illustrated) of one memory block areconnected to the bit lines BL, the string selection lines SSL, the wordlines WL, one or more ground selection lines GSL, and the common sourceline (not illustrated). The cell strings (not illustrated) of the memoryblocks BLK1 to BLKz may share the bit lines BL. For example, the bitlines BL may extend in the second direction and may be shared by thememory blocks BLK1 to BLKz.

The memory blocks BLK1 to BLKz may be selected by the row decoder 150illustrated in FIG. 1 . For example, the row decoder 150 may select amemory block, which corresponds to the received address ADDR, from amongthe memory blocks BLK1 to BLKz. A program operation and a read operationmay be performed on the selected memory block. Also, the erase operationaccording to example embodiments may be performed on a selectedsub-block included in the selected memory block.

Referring further to FIG. 2B, a memory block BLKn from among the memoryblocks BLK1 to BLKz of FIG. 2A is formed in a direction perpendicular toa substrate SUB. A common source line CSL is arranged on the substrateSUB, and gate electrodes GE and insulation layers IL are alternatelystacked on the substrate SUB. Also, a charge storage layer CS may beformed between the gate electrode GE and the insulation layer IL.

When the gate electrodes GE and the insulation layers IL, which arealternately stacked, are vertically patterned, a pillar P having a Vshape is formed. The pillar P is connected to the substrate SUB bypenetrating the gate electrodes GE and the insulation layers IL. Anouter portion O of the pillar P may include a semiconductor material andfunction as a channel, and an internal portion I of the pillar P mayinclude an insulation material such as silicon oxide.

The gate electrodes GE of the memory block BLKn may include the firstGIDL selection line GIDL_SL1, the ground selection line GSL, first tosixth word lines WL1 to WL6, the string selection line SSL, and thesecond GIDL selection line GIDL_SL2. The pillar P of the memory blockBLKn may be connected to the bit lines BL1 to BL3. Also, memory cellsconnected to the first to third word lines WL1 to WL3 may form the firstsub-block SB1, and memory cells connected to fourth to sixth word linesWL4 to WL6 may form the second sub-block SB2. The memory block BLKn maybe applied to the memory blocks BLK1 to BLKz of FIG. 2A.

Hereinafter, for convenience, it is illustrated that a sub-blockincludes word lines and memory cells connected thereto. However, thesub-block may be defined to include at least one of GIDL selectionlines, transistors connected to the GIDL selection lines, groundselection lines, transistors connected to the ground selection lines,string selection lines, and transistors connected to the stringselection lines.

However, the memory block BLKn of FIG. 2B is merely an example forconvenience of explanation, and one or more embodiments are not limitedthereto. It may be understood that the spirit of the inventive conceptmay be applied to various embodiments of the memory block BLKn.

FIG. 2C illustrates sub-blocks SB1 and SB2 in a memory block BLKn′formed according to a different method from that applied to the memoryblock BLKn. Referring to FIG. 2C, channels CH of the memory block BLKn′may include a lower channel CHa and an upper channel CHb. The lowerchannel CHa may be positioned between the upper channel CHb and thesubstrate SUB. For example, the lower channel CHa may be formed throughan etching process and a polysilicon deposition process before the upperchannel CHb is formed. After the lower channel CHa is formed, the upperchannel CHb may be formed on the lower channel CHa through an additionaletching process and the polysilicon deposition process. In this case,the memory cells corresponding to the lower channel CHa may be definedas the first sub-block SB1, and the memory cells corresponding to theupper channel CHb may be defined as the second sub-block SB2.

Channel widths of the lower channel CHa and the upper channel CHb mayhave the same profile. For example, a diameter d1 of the upper channelCHb corresponding to the sixth word line WL6 may be substantially thesame as or similar to a diameter d3 of the lower channel CHacorresponding to the third word line WL3. Also, a diameter d2 of theupper channel CHb corresponding to the fifth word line WL5 may besubstantially the same or similar to a diameter d4 of the lower channelCHa corresponding to the second word line WL2. Also, a diameter of thelower channel CHa of the first sub-block SB1 at a point, at which thefirst sub-block SB1 contacts the second sub-block SB2, may be greaterthan a diameter of the upper channel CHb of the second sub-block SB2.

However, the memory block BLKn′ of FIG. 2C is merely an example. Morechannels stacks may be formed as more channels are formed in stages, andthe memory block BLKn′ may include sub-blocks respectively correspondingto the channels.

Referring to FIG. 2D, a memory device MC according to an exampleembodiment may include a peripheral circuit region PCR, where aperipheral circuit is formed, a memory cell region MCR, and input/outputpads IOPAD. The peripheral circuit region PCR may include asemiconductor substrate SUB, a peripheral circuit (not illustrated)formed on an upper surface of the semiconductor substrate SUB, and alower insulation layer LIF covering the peripheral circuit. The memorycell region MCR may include a base layer BASE formed on an upper surfaceof the lower insulation layer LIF, a memory cell array (not illustrated)formed on an upper surface of the base layer BASE, and an upperinsulation layer UIF covering the memory cell array. The input/outputpads IOPAD may be formed on a lower surface of the semiconductorsubstrate SUB. In the memory device MC, the peripheral circuit may beformed on the semiconductor substrate SUB, and a size of the memorydevice MC may decrease by employing the COP structure in which thememory cell array is stacked on the peripheral circuit.

At least one memory block, which includes the sub-blocks on which theerase operation according to example embodiments is performed, may beformed in the memory cell region MCR. Also, to select the transmissionpath of the erase voltage, erase transistors controlled to be on/off maybe formed in the peripheral circuit region PCR.

FIG. 3 is a circuit diagram of the memory block BLKn of FIG. 2B.

Referring to FIG. 3 , the memory block BLKn may be a vertical NAND flashmemory and may include cell strings CSTR11, CSTR21, CSTR31, CSTR12,CSTR22, CSTR32, CSTR13, CSTR23 and CSTR33, the first to sixth word linesWL1 to WL6, the bit lines BL1 to BL3, the ground selection line GSL, thestring selection lines SSL1 to SSL3, the common source line CSL, thefirst GIDL selection line GIDL_SL1, and the second GIDL selection lineGIDL_SL2. Here, the number of cell strings, the number of word lines,the number of bit lines, the number of ground selection lines, thenumber of string selection lines, the number of first and second GIDLselection lines, and connections between such lines may vary accordingto example embodiments.

The cell strings CSTR11, CSTR21, CSTR31, CSTR12, CSTR22, CSTR32, CSTR13,CSTR23 and CSTR33 may be connected between the bit lines BL1 to BL3 andthe common source line CSL. Each cell string (e.g., the cell stringCSTR11) may include first and second GIDL selection transistors GIDL_ST1and GIDL_ST2, a string selection transistor SST, first to sixth memorycells MC1 to MC6, and a ground selection transistor GST that areconnected in series. The first to third memory cells MC1 to MC3 may formthe first sub-block SB1, and the fourth to sixth memory cells MC4 to MC6may form the second sub-block SB2. The memory device may perform apartial erase operation on each of the first sub-block SB1 and thesecond sub-block SB2. FIG. 3 illustrates that one memory block BLKnincludes two sub-blocks, e.g., the first sub-block SB1 and the secondsub-block SB2, but this is merely an example. The memory block BLKn mayinclude more sub-blocks than two.

In an example embodiment, the first and second GIDL selectiontransistors GIDL_ST1 and GIDL_ST2 may have a configuration forintentionally causing GIDL during the erase operation, and the erasevoltage may be effectively transmitted to the channels of the first andsecond sub-blocks SB1 and SB2 through the first and second GIDLselection transistors GIDL_ST1 and GIDL_ST2.

The string selection transistor SST may be connected to the stringselection lines SSL1 to SSL3. The memory cells MC1 to MC6 may berespectively connected to the first to sixth word lines WL1 to WL6. Theground selection transistor GST may be connected to the ground selectionline GSL. In an example embodiment, in the first GIDL selectiontransistor GIDL_ST1, a gate may be connected to the first GIDL selectionline GIDL_SL1, and a source may be connected to the common source lineCSL. In the second GIDL selection transistor GIDL_ST2, a gate may beconnected to the second GIDL selection line GIDL_SL2, and a drain may beconnected to the corresponding bit lines BL1 to BL3.

The word lines (e.g., the word line WL1) having the same height may becommonly connected, and the string selection lines SSL1 to SSL3 may beseparated. When the memory cells connected to the first word line WL1and included in the cell strings CSTR11, CSTR12, and CSTR13 areprogrammed, the first word line WL1 and the first string selection lineSSL1 may be selected.

The memory device according to an embodiment may select the transmissionpath of the erase voltage based on the positions of the first and secondsub-blocks SB1 and SB2 and may perform the erase operation by using theselected transmission path.

FIG. 4 is a flowchart of an operation method of a memory device,according to an example embodiment.

Referring to FIG. 4 , in operation S100, the memory device may identifya position of a target sub-block that is an erase target. For example,the memory device may identify whether the target sub-block is adjacentto a bit line or a common source line. As another example, the memorydevice may identify whether the target sub-block is adjacent to a stringselection line or a ground selection line. In some embodiments, thememory device may identify the position of the target sub-block byreferencing position information regarding each sub-block that is storedin advance. In operation S110, the memory device may select an erasemethod based on the position of the target sub-block. In operation S120,the memory device may perform the erase operation on the targetsub-block according to the selected erase method. For example, when thetarget sub-block is adjacent to the bit line, the memory device mayselect the bit line as the transmission path of the erase voltage andmay perform the erase operation on the target sub-block. When the targetsub-block is adjacent to the common source line, the memory device mayselect the common source line as the transmission path of the erasevoltage and may perform the erase operation on the target sub-block. Insome embodiments, the memory device may select the bit line and thecommon source line as the transmission paths of the erase voltageregardless of the position of the target sub-block and may perform theerase operation on the target sub-block.

FIG. 5 is a diagram of a cell string CSTR included in a memory block,according to an example embodiment.

Referring to FIG. 5 , the cell string CSTR may include the first GIDLselection transistor GIDL_ST1 and the ground selection transistor GSTfor controlling an electrical connection between the common source lineCSL and the cell string CSTR, may include the second GIDL selectiontransistor GIDL_ST2 and the string selection transistor SST forcontrolling an electrical connection between the bit line BL and thecell string CSTR, and may include the memory cells MC. In detail, thefirst GIDL transistor GIDL_ST1 may be coupled between the common sourceline CSL and the ground selection transistor GST, and the second GIDLtransistor GIDL_ST2 may be coupled to the bit line BL and the stringselection transistor SST.

The cell string CSTR may be coupled to a first erase transistor E_TR1that is controlled to be on/off, according to a first gate voltageVG_ER1 to selectively apply the erase voltage to the common source lineCSL. The first erase transistor E_TR1 may be coupled to a first terminalT1 to which the erase voltage is applied. The cell string CSTR may becoupled to a second erase transistor E_TR2 that is controlled to beon/off, according to a second gate voltage VG_ER2 to selectively applythe erase voltage to the bit line BL. The second erase transistor E_TR2may be coupled to a second terminal T2 to which the erase voltage isapplied.

In some embodiments, when the memory block including the cell stringCSTR has a COP structure, the memory block may be stacked on aperipheral circuit. For example, in the peripheral circuit, the pagebuffer circuit 120, the control logic 130, the voltage generator 140,the row decoder 150, and the data input/output circuit 160 of FIG. 1 maybe formed. Also, the first and second erase transistors E_TR1 and E_TR2may be formed in a region (hereinafter, referred to as a peripheralcircuit region) where the peripheral circuit is formed. Detaileddescriptions thereof will be provided below.

Arrangements of the first and second erase transistors E_TR1 and E_TR2of FIG. 5 are merely examples, and one or more embodiments are notlimited thereto. Various arrangements may be applied to the cell stringCSTR to enable the selection of at least one of the common source lineCSL and the bit line BL as the transmission path of the erase voltage.

FIGS. 6A and 6B are diagrams for explaining an erase operation performedon the first sub-block SB1 in the cell string CSTR of FIG. 5 accordingto example embodiments.

Referring to FIG. 6A, when the erase operation is performed on the firstsub-block SB1, the common source line CSL may be selected as atransmission path of an erase voltage V_ERS, based on the position ofthe first sub-block SB1 that is adjacent to the common source line CSL.A detailed operation will be described with reference further to FIG.6B.

Referring further to FIG. 6B, the erase voltage V_ERS may be applied tothe first and second terminals T1 and T2 from a first time point t1. Thefirst gate voltage VG_ER1 may be applied to a gate of the first erasetransistor E_TR1 from the first time point t1, wherein the first gatevoltage VG_ER1 may be increased from 0 V (or a low level) to a levelfrom the first time point t1 to third time point t3, at which the erasevoltage V_ERS is added to a certain threshold voltage V_(th). Thus, thefirst erase transistor E_TR1 may be turned on. For example, the erasevoltage V_ERS may be about 18 V, and the threshold voltage V_(th) may beabout 3 V. A second gate voltage VG_ER2 having a voltage of 0 V (or thelow level) may be applied to a gate of the second erase transistorE_TR2, and thus, the second erase transistor E_TR2 may be turned off.The common source line CSL may be selected as the transmission path ofthe erase voltage V_ERS, and a voltage of the common source line CSL maybe increased from 0 V (or the low level) to the level of the erasevoltage V_ERS from the first time point t1 to the third time point t3.The voltage of 0 V (or the low level) may be applied to the groundsource line GSL and the first GIDL selection line GIDL_SL1 from thefirst time point t1 to a second time point t2, and the ground sourceline GSL and the first GIDL selection line GIDL_SL1 may be floated fromthe second time point t2. Hereinafter, controlling of the groundselection line GSL and the first GIDL selection line GIDL_SL1 to have afloating start timing (the second time point t2), which is later thanfloating start timings (the first time point t1) of the bit lines BL,the second GIDL selection line GIDL_SL2, the string selection line SSL,and the fourth to sixth word lines WL4 to WL6 is to effectively providethe erase voltage V_ERS to the channel of the second sub-block SB2 bycausing a voltage difference between the channel of the first sub-blockSB1 and the second sub-block SB2 from the first time point t1 to thesecond time point t2. The ground source line GSL and the first GIDLselection line GIDL_SL1 may have a floating voltage of which a level isobtained by subtracting the GIDL voltage V_GIDL from the erase voltageV_ERS. The GIDL voltage V_GIDL is generated because of the GIDL from thefirst GIDL selection transistor GIDL_ST1 and is to effectively providethe erase voltage V_ERS to the channel of the second sub-block SB2 bycausing the voltage difference between the channel of the firstsub-block SB1 and the second sub-block SB2 even after the third timepoint t3.

Because the first sub-block SB1 is an erase target sub-block, thevoltage of 0 V (or the low level) may be applied to the first to thirdword lines WL1 to WL3. Because the second sub-block SB2 is not the erasetarget sub-block, the fourth to sixth word lines WL4 to WL6 may befloated to the erase voltage V_ERS from the first time point t1.Likewise, the string selection line SSL, the second GIDL selection lineGIDL_SL2, and the bit line BL may be floated from the erase voltageV_ERS from the first time point t1.

Through the above operation, the channels of the first sub-block SB1 andthe second sub-block SB2 may be sequentially boosted to the erasevoltage V_ERS in a direction from the common source line CSL to the bitline BL, and the memory cells MC of the first sub-block SB1 may beerased.

An application start timing (the first time point t1), in which theerase voltage is applied to the first and second terminals T1 and T2,may be identical to floating start timings (the first time point t1) ofthe bit line BL, the second GIDL selection line GIDL_SL2, the stringselection line SSL, and the fourth to sixth word lines WL4 to WL6.

FIGS. 7A and 7B are diagrams for explaining the erase operationperformed on the second sub-block SB2 in the cell string CSTR of FIG. 5according to example embodiments. Hereinafter, comparative examples willbe described first before example embodiments of FIGS. 7A and 7B aredescribed. In comparative examples, it is assumed that, when the secondsub-block SB2 is erased, the erase voltage V_ERS is transmitted throughthe common source line CSL, as illustrated in FIGS. 6A and 6B. Incomparative examples, when 0 V (or the low level) is applied to theground selection line GSL and the first GIDL selection line GIDL_SL1from the first time point t1 to the second time point t2 to effectivelytransmit the erase voltage V_ERS to the channel of the second sub-blockSB2, a voltage difference between the ground selection line GSL and thefirst GIDL selection line GIDL_SL1 and other lines, to which a voltageincreased to be closer to the erase voltage V_ERS is applied, may berelatively great, and thus, charges stored in the memory cells MC of thefirst sub-block SB1 may be lost. The loss of changes may result in thedegradation in the reliability of the data of the memory device, and theembodiments of FIGS. 7A and 7B may be applied to solve the problemstated in comparative examples. Hereinafter, the descriptions providedwith reference to FIGS. 6A and 6B are omitted.

Referring to FIG. 7A, when the erase operation is performed on thesecond sub-block SB2, the bit line BL may be selected as thetransmission path of the erase voltage V_ERS, based on the position ofthe second sub-block SB2 adjacent to the bit line BL. A detailedoperation will be described with reference to FIG. 7B.

Referring further to FIG. 7B, the second gate voltage VG_ER2, which isincreased from 0 V (or the low level) to a level from the first timepoint t1 to the third time point t3, at which the erase voltage V_ERS isadded to a certain threshold voltage Vth, may be applied to a gate ofthe second erase transistor E_TR2, and thus, the second erase transistorE_TR2 may be turned on. The first gate voltage VG_ER1 of 0 V (or the lowlevel) may be applied to the gate of the first erase transistor E_TR1,and the first erase transistor E_TR1 may be turned off. The bit line BLmay be selected as the transmission path of the erase voltage V_ERS, andthe voltage of the bit line BL may be increased from 0 V (or the lowlevel) to the erase voltage V_ERS from the first time point t1 to thethird time point t3. The voltage of 0 V (or the low level) may beapplied to the string selection line SSL and the second GIDL selectionline GIDL_SL2 from the first time point t1 to the second time point t2,and the string selection line SSL and the second GIDL selection lineGIDL_SL2 may be floated from the second time point t2. The stringselection line SSL and the second GIDL selection line GIDL_SL2 may havethe floating voltage having a level obtained by subtracting the GIDLvoltage V_GIDL from the erase voltage V_ERS. The GIDL voltage V_GIDL maybe generated because of the GIDL from the second GIDL selectiontransistor GIDL_ST2.

Because the second sub-block SB2 is the erase target sub-block, thevoltage of 0 V (or the low level) may be applied to the fourth to sixthword lines WL4 to WL6. Because the first sub-block SB1 is not the erasetarget sub-block, the first to third word lines WL1 to WL3 may befloated to the erase voltage V_ERS from the first time point t1.Likewise, the ground selection line GSL, the first GIDL selection lineGIDL_SL1, and the common source line CSL may be floated to the erasevoltage V_ERS from the first time point t1.

Through the above operation, the channels of the second sub-block SB2and the first sub-block SB1 may be sequentially boosted to the erasevoltage V_ERS in a direction from the bit line BL to the common sourceline CSL, and the memory cells MC of the second sub-block SB2 may beerased.

FIGS. 8A and 8B are diagrams for explaining the erase operationperformed on the second sub-block SB2 in the cell string CSTR of FIG. 5according to example embodiments.

Referring to FIG. 8A, when the erase operation is performed on thesecond sub-block SB2, the common source line CSL and the bit line BL maybe selected as the transmission paths of the erase voltage V_ERS. Adetailed operation may be described with reference further to FIG. 8B.

Referring further to FIG. 8B, the first and second gate voltages VG_ER1and VG_ER2, which are increased from 0 V (or the low level) to the levelfrom the first time point t1 to the third time point t3, at which theerase voltage V_ERS is added to the certain threshold voltage Vth, maybe applied to the gates of the first and second erase transistors E_TR1and E_TR2, and thus, the first and second erase transistors E_TR1 andE_TR2 may be turned on. The common source line CSL and the bit line BLmay be selected as the transmission paths of the erase voltage V_ERS,and the voltages of the common source line CSL and the bit line BL maybe increased from 0 V (or the low level) to the level of the erasevoltage V_ERS from the first time point t1 to the third time point t3.The voltage of 0 V (or the low level) may be applied to the stringselection line SSL and the second GIDL selection line GIDL_SL2 from thefirst time point t1 to the second time point t2, and the stringselection line SSL and the second GIDL selection line GIDL_SL2 may befloated from the second time point t2. The string selection line SSL andthe second GIDL selection line GIDL_SL2 may have a floating voltage,which has a level obtained by subtracting the GIDL voltage V_GIDL fromthe erase voltage V_ERS. The GIDL voltage V_GIDL may be generatedbecause of the GIDL from the second GIDL selection transistor GIDL_ST2.

Because the second sub-block SB2 is the erase target sub-block, thevoltage of 0 V (or the low level) may be applied to the fourth to sixthword lines WL4 to WL6. Because the first sub-block SB1 is not the erasetarget sub-block, the first to third word lines WL1 to WL3 may befloated to the erase voltage V_ERS from the first time point t1.Likewise, the ground selection GSL and the first GIDL selection lineGIDL_SL1 may be floated to the erase voltage V_ERS from the first timepoint t1.

Through the above operation, in a direction from the common source lineCSL to the bit line BL and a direction from the bit line BL to thecommon source line CSL, that is, in both directions, the channels of thefirst sub-block SB1 and the second sub-block SB2 may be boosted to theerase voltage V_ERS, and the memory cells MC of the second sub-block SB2may be erased.

When the erase operation of the first sub-block SB1 is performed, theembodiments of FIGS. 8A and 8B may be applied, and detailed descriptionsthereof will be omitted.

FIGS. 9A to 9C are diagrams of examples of sub-blocks included in amemory block on which an erase operation is performed, according to anexample embodiment.

Referring to FIG. 9A, a memory block BLKn_a may include the firstsub-block SB1 and the second sub-block SB2. For example, the firstsub-block SB1 and the second sub-block SB2 may be coupled to the samenumber of word lines, respectively. As another example, the number ofmemory cells included in the first sub-block SB1 may be identical to thenumber of memory cells included in the second sub-block SB2. The firstsub-block SB1 may be coupled to three word lines WL1 to WL3 (the firstto third three word lines WL1 to WL3) and the second sub-block SB2 maybe coupled to three word lines (the fourth to sixth word lines WL4 toWL6). The second sub-block SB2 may be adjacent to the bit line BL, and aposition of the second sub-block SB2 may be defined as being adjacent tothe bit line BL. The first sub-block SB1 may be adjacent to the commonsource line CSL, and a position of the first sub-block SB1 may bedefined as being adjacent to the common source line CSL. Hereinafter,for consistency, the position of each sub-block is described withrespect to the bit line BL or the common source line CSL, but one ormore embodiments are not limited thereto. The positions of thesub-blocks may be described with respect to the string selection line orthe string selection transistor instead of the bit line BL and to theground selection line or the ground selection transistor instead of thecommon source line CSL.

Referring to FIG. 9B, a memory block BLKn_b may include a firstsub-block SB1 to a k^(th) sub-block SBk (k is a natural number greaterthan 2). That is, the memory block BLKn_b may include three or moresub-blocks SB1 to SBk. The sub-blocks SB1 to SBk may be respectivelycoupled to the same number of word lines, and the number of memory cellsincluded in the sub-blocks SB1 to SBk may be identical to each other.However, this is merely an example, and various embodiments may be made.For example, the number of word lines connected to the sub-blocks SB1 toSBk may be different from each other, and the number of memory cellsincluded in the sub-blocks SB1 to SBk may be different from each other.A position of each of the sub-blocks SB1 to SBk may be defined withrespect to the bit line BL or the common source line CSL. For example,first to j^(th) sub-blocks SB1 to SBj (where, j is a natural number lessthan k−1) may be defined to be adjacent to the common source line CSL,and (j+1)^(th) to k^(th) sub-blocks SB(j+1) to SBk may be defined to beadjacent to the bit line BL.

Information regarding the positions of the sub-blocks SB1 to SBk may bedetermined in advance through a memory test operation, and theinformation may be periodically or non-periodically updated for aneffective erase operation, according to an operation environment of thememory device. In an example embodiment, the information regarding thepositions of the sub-blocks SB1 to SBk may include information regardingthe selected transmission path of the erase voltage during the eraseoperation performed on each of the sub-blocks SB1 to SBk.

Referring to FIG. 9C, a memory block BLKn_c may include the firstsub-block SB1 and the second sub-block SB2 connected to the differentnumbers of word lines. For example, the first sub-block SB1 may beconnected to p word lines WL1 to WLp, and the second sub-block SB2 maybe connected to q word lines WL(p+1) to WL(p+q). For example, a ratio ofthe number of word lines of the first sub-block SB1 to the number ofword lines of the second sub-block SB2 may vary, for example, “40:60,”“50:50,” “60:40,” and the like.

FIG. 10 is a flowchart of an operation method of a memory device,according to an example embodiment.

Referring to FIG. 10 , in operation S200, the memory device may identifythe position of the target sub-block that is the erase target sub-block.When the target sub-block is at a certain position, the memory block mayperform operation S210 when, for example, the target sub-block isbetween the bit line and the common source line. In operation S210, thememory device may identify cell types of adjacent sub-blocks of thetarget sub-block. In operation S220, the memory device may select anerase method of the target sub-block, based on the position of thetarget sub-block and the cell types of the adjacent sub-blocks. Inoperation S230, the memory device may perform the erase operation on thetarget sub-block, according to the selected erase method.

FIGS. 11A and 11B are diagrams for explaining an erase method of thesecond sub-block SB2, according to example embodiments.

Referring to FIG. 11A, the memory block may include the first to thirdsub-blocks SB1 to SB3, the second sub-block SB2 may be stacked on thefirst sub-block SB1, and the third sub-block SB3 may be stacked on thesecond sub-block SB2. When the erase operation is performed on thesecond sub-block SB2, the memory device may identify cell types of thefirst and third sub-blocks SB1 and SB3 that are adjacent to the secondsub-block SB2 to select the transmission path of the erase voltage. Forexample, the cell type of the first sub-block SB1 may be higher thanthat of the third sub-block SB3. In detail, the memory cells of thefirst sub-block SB1 are multi-level cells and store two-bit data, andthe memory cells of the third sub-block SB3 may be single-level cellsand store one-bit data. The memory device may select the transmissionpath of the erase voltage, based on the cell types of the first andthird sub-blocks SB1 and SB3.

The third sub-block SB3 operated as the single-level cells may havegreater gaps between threshold voltage dispersions than the firstsub-block SB1 operated as the multi-level cells, and thus, adeterioration degree of data of the third sub-block SB3 may berelatively less than that of the first sub-block SB1 because of adifference between voltages generated during the erase operation.Accordingly, the memory device may select the bit line BL, which isadjacent to the third sub-block SB3, as the transmission path of theerase voltage V_ERS and may perform the erase operation on the secondsub-block SB2, by considering the third sub-block SB3 having arelatively less deterioration degree because of the erase operation.

Referring to FIG. 11B, the cell type of the first sub-block SB1 may havea lower level than the cell type of the third sub-block SB3, unlike theillustration of FIG. 11A. In detail, the memory cells of the firstsub-block SB1 may be operated as the single-level cells and may storeone-bit data, and the memory cells of the third sub-block SB3 may beoperated as the multi-level cells and store two-bit data. The memorydevice may select the transmission path of the erase voltage, based onthe cell types of the first and third sub-blocks SB1 and SB3. The memorydevice may select the common source line CSL, which is adjacent to thefirst sub-block SB1, as the transmission path of the erase voltage V_ERSand may perform the erase operation on the second sub-block SB2, byconsidering the first sub-block SB1 having the relatively lessdeterioration degree because of the erase operation.

The cell types of the first and third sub-blocks SB1 and SB3 of FIGS.11A and 11B are merely examples, and one or more embodiments are notlimited thereto. The spirit of the inventive concept may be applied whenthe first and third sub-blocks SB1 and SB3 have different cell typessuch as a triple-level cell and a quadruple-level cell type.

In some embodiments, when the memory block includes three or moresub-blocks, the transmission path of the erase voltage, which isselected when each sub-block is designated as an erase target sub-block,may be determined based on sub-block operation information indicating acell type of each sub-block and a position of each sub-block, and thus,the transmission path may be stored in the memory device in advance assub-block erase information. When the memory device performs the eraseoperation, a transmission path of the erase voltage that matches withthe target sub-block may be quickly selected by referencing thesub-block erase information.

FIG. 12 is a flowchart of an operation method of a memory system,according to an example embodiment.

Referring to FIG. 12 , the memory system may include a memory controller300 and a memory device 310. In operation S300, the memory controller300 may transmit, to the memory device 310, the sub-block operationinformation of the memory block of the memory device 310. The sub-blockoperation information may indicate a cell type of each sub-block. Insome embodiments, the memory controller 300 may change cell types of thesub-blocks in the memory block by considering a request from a host, anoperation environment of the memory system, or the like, and maytransmit sub-block operation information, which includes contentregarding the changed cell types, to the memory device 310. In operationS310, the memory device 310 may update sub-block erase information,based on the sub-block operation information. As described above, wheneach sub-block is selected as an erase target sub-block, the sub-blockerase information may indicate the transmission path of the erasevoltage selected for the erase operation. In operation S320, the memorycontroller 300 may transmit, to the memory device 310, an erase commandregarding the target sub-block. In operation S330, the memory device 310may perform the erase operation on the target sub-block by using theupdated sub-block erase information in response to the erase command.

FIG. 13 is a block diagram of a Solid State Drive (SSD) system 400according to an example embodiment.

Referring to FIG. 13 , the SSD system 400 may include a host 410 and anSSD 420. The SSD 420 may exchange signals with the host 410 through asignal connector and may receive power through a power connector. TheSSD 420 may include an SSD controller 421, an auxiliary power supply422, and first to s^(th) memory devices 423_1 to 423_s (s is a naturalnumber greater than 1). Each of the first to s^(th) memory devices 423_1to 423_s may include one or more memory devices disclosed previously. Insome examples, the first memory device 423_1 may employ one memorydevice 100 in FIG. 1 or a plurality of memory devices. In this case, theembodiments of FIGS. 1, 2A to 2D, 3 to 5, 6A, 6B, 7A, 7B, 8A, 8B, 9A to9C, 10, 11A, 11B and 12 may be applied to the first to s^(th) memorydevices 423_1 to 423_s. For example, the first to s^(th) memory devices423_1 to 423_s may include first to s^(th) sub-block erase informationERS_Info.1˜ERS_Info.s indicating the transmission path of the erasevoltage selected during the erase operation performed on each sub-blockof the memory block included in each of the first to s^(th) memorydevices 423_1 to 423_s. As described above, the transmission path of theerase voltage, which is selected during the erase operation performed oneach sub-block, may be determined by considering at least one of theposition of the sub-block and the cell types of the adjacent sub-blocks.The first to s^(th) memory devices 423_1 to 423_s may perform the eraseoperation on the target sub-block by using the first to s^(th) sub-blockerase information ERS_Info.1 to ERS_Info.s.

FIG. 14 is a cross-sectional view for explaining a memory device 2400 asan example of the memory device 100 of FIG. 1 according to exampleembodiments.

Referring to FIG. 14 , the memory device 2400 may have a Chip-to-Chip(C2C) structure. The C2C structure may indicate that an upper chipincluding the cell region CELL is manufactured on a first wafer, a lowerchip including the peripheral circuit region PERI is manufactured on asecond wafer that is different from the first wafer, and then the upperchip and the lower chip are connected to each other according to abonding method. For example, the bonding method may indicate a methodwhereby a bonding metal, which is formed on an uppermost metal layer ofthe upper chip, is electrically connected to a bonding metal, which isformed on an uppermost metal layer of the lower chip. For example, whenthe bonding metal includes copper (Cu), the bonding method may be aCu—Cu bonding method, and the bonding metal may include aluminum ortungsten.

The peripheral circuit region PERI and the cell region CELL of thememory device 2400 may each include an external pad bonding area PA, aword line bonding area WLBA, and a bit line bonding area BLBA.

The peripheral circuit region PERI may include a first substrate 2210,an interlayer insulation layer 2215, circuit elements 2220 a, 2220 b,and 2220 c formed on the first substrate 2210, first metal layers 2230a, 2230 b, and 2230 c respectively connected to the circuit elements2220 a, 2220 b, and 2220 c, second metal layers 2240 a, 2240 b, and 2240c formed on the first metal layers 2230 a, 2230 b, and 2230 c. Each ofthe circuit elements 2220 a, 2220 b, and 2220 c may correspond to one ormore transistors. In an embodiment, the first metal layers 2230 a, 2230b, and 2230 c may include tungsten having a relatively high resistance,and the second metal layers 2240 a, 2240 b, and 2240 c may includecopper having a relatively low resistance.

In the present disclosure, the first metal layers 2230 a, 2230 b, and2230 c and the second metal layers 2240 a, 2240 b, and 2240 c areillustrated only, but one or more embodiments are not limited thereto.At least one metal layer may be further formed on the second metallayers 2240 a, 2240 b, and 2240 c. At least part of the at least onemetal layer formed on the second metal layers 2240 a, 2240 b, and 2240 cmay include aluminum having a lower resistance than copper included inthe second metal layers 2240 a, 2240 b, and 2240 c.

The interlayer insulation layer 2215 may be formed on the firstsubstrate 2210 to cover the circuit elements 2220 a, 2220 b, and 2220 c,the first metal layers 2230 a, 2230 b, and 2230 c, and the second metallayers 2240 a, 2240 b, and 2240 c, and may include an insulationmaterial such as silicon oxide or silicon nitride.

Lower bonding metals 2271 b and 2272 b may be formed on the second metallayer 2240 b in the word line bonding area WLBA. In the word linebonding area WLBA, the lower bonding metals 2271 b and 2272 b of theperipheral circuit region PERI may be electrically connected to upperbonding metals 2371 b and 2372 b of the cell region CELL according tothe bonding method, and the lower bonding metals 2271 b and 2272 b andthe upper bonding metals 2371 b and 2372 b may each include aluminum,copper, tungsten, or the like.

The cell region CELL may provide at least one memory block. The cellregion CELL may include a second substrate 2310 and a first commonsource line 2320. On the second substrate 2310, word lines 2333 to 2336(WL1 to WL4) may be stacked in a direction (a Z-axis direction)perpendicular to an upper surface of the second substrate 2310. A stringselection line 2337 (SSL) and a ground selection line 2332 (GSL) may berespectively arranged on upper and lower portions of the word lines 2333to 2336 (WL1 to WL4). The string selection line 2337 (SSL), the groundselection line 2332 (GSL), and the word lines 2333 to 2336 (WL1 to WL4)may be arranged between first and second GIDL selection lines 2331 and2338 (GIDL_SL1 and GIDL_SL2).

In the bit line bonding area BLBA, the channel structure CHS may extendin a direction perpendicular to the second substrate 2310 and maypenetrate the word lines 2333 to 2336 (WL1 to WL4), the first and secondGIDL selection lines 2331 and 2338 (GIDL_SL1 and GIDL_SL2), the stringselection line 2337 (SSL), and the ground selection line 2332 (GSL). Thechannel structure CHS may include a data storage layer, a channel layer,a buried insulation layer, and the like, and the channel layer may beelectrically connected to a first metal layer 2350 c and a second metallayer 2360 c. For example, the first metal layer 2350 c may be a bitline contact, and the second metal layer 2360 c may be a first bit line.In an embodiment, the first bit line 2360 c may extend in a firstdirection (a Y-axis direction) parallel to an upper surface of thesecond substrate 2310.

In an embodiment illustrated in FIG. 14 , an area where the channelstructure CHS, the first bit line 2360 c, and the like are arranged maybe defined as the bit line bonding area BLBA. The first bit line 2360 cmay be electrically connected to the circuit elements 2220 c providingthe page buffer 2393 in the peripheral circuit region PERI in the bitline bonding area BLBA. For example, the first bit line 2360 c may beconnected to upper bonding metals 2371 c and 2372 c in the peripheralcircuit region PERI, and the upper bonding metals 2371 c and 2372 c maybe connected to lower bonding metals 2271 c and 2272 c connected to thecircuit elements 2220 c of the page buffer 2393.

In the word line bonding area WLBA, the word lines 2332 to 2337 (WL1 toWL6) may extend in a second direction (an X-axis direction) parallel tothe upper surface of the second substrate 2310 and may be connected tocell contact plugs 2341 to 2347 (2340). The word lines 2332 to 2337 (WL1to WL6) and the cell contact plugs 2340 may be connected to pads thatare provided as at least some of the word lines 2333 to 2336 (WL1 toWL4) extend in different lengths in the second direction. The firstmetal layer 2350 b and the second metal layer 2360 b may be sequentiallyconnected to upper portions of the cell contact plugs 2340 connected tothe word lines 2333 to 2336 (WL1 to WL4). In the word line bonding areaWLBA, the cell contact plugs 2340 may be connected to the peripheralcircuit region PERI through the upper bonding metals 2371 b and 2372 bof the cell region CELL and the lower bonding metals 2271 b and 2272 bof the peripheral circuit region PERI.

The cell contact plugs 2340 may be electrically connected to the circuitelements 2220 b providing the row decoder 2394 in the peripheral circuitregion PERI. In an embodiment, operation voltages of the circuitelements 2220 b providing the row decoder 2394 may be different fromoperation voltages of circuit elements 2220 c providing the page buffer2393. For example, the operation voltages of the circuit elements 2220 cproviding the page buffer 2393 may be greater than the operationvoltages of the circuit elements 2220 b providing the row decoder 2394.

In the external pad bonding area PA, the common source line contact plug2380 may be arranged. The common source line contact plug 2380 mayinclude a conductive material such as metal, a metal compound, orpolysilicon and may be electrically connected to the common source line2320. The first metal layer 2350 a and the second metal layer 2360 a maybe sequentially stacked on the common source line contact plug 2380. Forexample, an area where the source line contact plug 2380, the firstmetal layer 2350 a, and the second metal layer 2360 a are arranged maybe defined as the external pad bonding area PA.

In the external pad bonding area PA, input/output pads 2205 and 2305 maybe arranged. Referring to FIG. 14 , a lower insulation layer 2201covering a lower surface of the first substrate 2210 may be formed on alower portion of the first substrate 2210, and the first input/outputpad 2205 may be formed on the lower insulation layer 2201. The firstinput/output pad 2205 may be connected to at least one of the circuitelements 2220 a, 2220 b, and 2220 c arranged in the peripheral circuitregion PERI through the first input/output contact plug 2203 and may beseparated from the first substrate 2210 by the lower insulation layer2201. Also, a side insulation layer may be arranged between the firstinput/output contact plug 2203 and the first substrate 2210 and mayelectrically separate the first input/output contact plug 2203 from thefirst substrate 2210.

Referring to FIG. 14 , an upper insulation layer 2301 covering an uppersurface of the second substrate 2310 may be formed on an upper portionof the second substrate 2310, and the second input/output pad 2305 maybe arranged on the upper insulation layer 2301. The second input/outputpad 2305 may be connected to at least one of the circuit elements 2220a, 2220 b, and 2220 c arranged in the peripheral circuit region PERIthrough a second input/output contact plug 2303.

According to example embodiments, in an area where the secondinput/output contact plug 2303 is arranged, the second substrate 2310,the first common source line 2320, and the like may not be arranged.Also, the second input/output pad 2305 may not overlap the word lines2333 to 2336 (WL1 to WL4) in the third direction (the Z-axis direction).Referring to FIG. 14 , the second input/output contact plug 2303 may beseparated from the second substrate 2310 in a direction parallel to theupper surface of the second substrate 2310 and may be connected to thesecond input/output pad 2305 by penetrating the interlayer insulationlayer 2315 in the cell region CELL.

According to embodiments, the first input/output pad 2205 and the secondinput/output pad 2305 may be selectively formed. For example, the memorydevice 2400 may only include the first input/output pad 2205 arranged onthe first substrate 2210 or may only include the second input/output pad2305 arranged on the second substrate 2310. Alternatively, the memorydevice 2400 may include both the first input/output pad 2205 and thesecond input/output pad 2305.

In the external pad bonding area PA and the bit line bonding area BABArespectively included in the cell region CELL and the peripheral circuitregion PERI, metal patterns of the uppermost metal layer may be dummypatterns, or the uppermost metal layer may be omitted.

In the external pad bonding area PA, lower metal patterns 2273 a of theperipheral circuit region PERI electrically connected to upper bondingmetals 2371 a and 2372 a of the cell region CELL may be formed on theuppermost metal layer in the peripheral circuit region PERI,corresponding to upper metal patterns 2373 a formed on the uppermostmetal layer of the cell region CELL. The lower metal pattern 2273 aformed on the uppermost metal layer in the peripheral circuit regionPERI may not be connected to a separate contact in the peripheralcircuit region PERI. As described, in the external pad bonding area PA,upper metal patterns (e.g., 2373 a) having the same shapes as the lowermetal patterns (e.g., 2273 a) in the peripheral circuit region PERI maybe formed on the upper metal layer in the cell region CELL,corresponding to the lower metal pattern (e.g., 2273 a) formed on theuppermost metal layer in the peripheral circuit region PERI.

In the external pad bonding area PA, the upper metal patterns 2373 a ofthe cell region CELL may be electrically connected to lower bondingmetals 2271 a and 2272 a of the peripheral circuit region PERI.

The lower bonding metals 2271 b and 2272 b may be formed on the secondmetal layer 2240 b of the word line bonding area WLBA. In the word linebonding area WLBA, the lower bonding metals 2271 b and 2272 b of theperipheral circuit region PERI may be electrically connected to theupper bonding metals 2371 b and 2372 b of the cell region CELL accordingto the bonding method.

Also, in the bit line bonding area BLBA, the upper metal pattern 2392,which has the same shape as the lower metal pattern 2252 of theperipheral circuit region PERI, may be formed on the uppermost metallayer of the cell region CELL, corresponding to the lower metal pattern2252 formed on the uppermost metal layer of the peripheral circuitregion PERI. Contacts may not be formed on the upper metal pattern 2392formed on the uppermost metal layer of the cell region CELL.

In an example embodiment, the first sub-block SB1 may be adjacent to thefirst common source line CSL (2320) or the second substrate 2310 and mayinclude the memory cells MC connected to the first and second word lines2333 and 2334 (WL1 and WL2). The second sub-block SB2 may be adjacent tothe first bit line 2360 c or the peripheral circuit region PERI and mayinclude the memory cells MC connected to the third and fourth word lines2335 and 2336 (WL3 and WL4). However, this is merely an example, and oneor more embodiments are not limited thereto. The first sub-block SB1 andthe second sub-block SB2 may further include memory cells connected to agreater number of word lines.

When the memory device 2400 performs the erase operation, and when thetarget sub-block is the first sub-block SB1, the first common sourceline 2320 may be selected as the transmission path of the erase voltage,and when the target sub-block is the second sub-block SB2, the first bitline 2360 c may be selected as the transmission path of the erasevoltage. The one or more embodiments of the inventive concept may beapplied to the memory device 2400.

In example embodiments, a memory cell array or a memory block describedwith reference to FIGS. 1, 2A to 2D, and 3 may be included in the cellregion CELL. Peripheral circuits (e.g., the page buffer circuit 120, thecontrol logic 130, the voltage generator 140, the row decoder 150, andthe data input/output circuit 160) described with reference to FIG. 1may be included in the peripheral circuit region PERI.

FIGS. 15A to 15D are cross-sectional views of memory devices 3400 a to3400 c having a C2C structure as an example of the memory device 100 ofFIG. 1 according to example embodiments.

Referring to FIG. 15A, compared to the memory device 2400 of FIG. 14 ,the memory device 3400 a may include two or more upper chips includingcell regions. In detail, the memory device 3400 a may have a structurein which a first upper chip including a first cell region CELL1, asecond upper chip including a second cell region CELL2, and a lower chipincluding the peripheral circuit region PERI are connected according tothe bonding method. However, the number of upper chips is not limitedthereto. Regarding the descriptions of the first cell region CELL1 andthe second cell region CELL2, the descriptions already provided withreference to FIG. 14 will not be repeated. Hereinafter, the cell regionCELL may denote at least one of the first cell region CELL1 and thesecond cell region CELL2.

In the bit line bonding area BLBA, the cell region CELL may include alower channel LCH and an upper channel UCH that are connected to eachother. The lower channel LCH and the upper channel UCH may be connectedto each other and may form one channel structure CHS. That is, unlikethe channel structure CHS of FIG. 14 , the channel structure CHS of FIG.15 may be formed through a process regarding the upper channel UCH and aprocess regarding the lower channel LCH. In the first cell region CELL1,the lower channel LCH may extend in a direction perpendicular to anupper surface of a third substrate 3610 and may penetrate a secondcommon source line 3620, a first GIDL selection line 3631, a secondground selection line 3632, and second lower word lines 3633 and 3634.The lower channel LCH may include the data storage layer, the channellayer, the buried insulation layer, and the like, and may be connectedto the upper channel UCH. The upper channel UCH may penetrate secondupper word lines 3635 and 3636, a second string selection line 3637, anda second GIDL selection line 3638. The upper channel UCH may include thedata storage layer, the channel layer, the buried insulation layer, andthe like, and the channel layer of the upper channel UCH may beelectrically connected to a third metal layer 3650 c and a fourth metallayer 3660 c. The longer the channel lengths are, the more difficult itis to form channels having uniform widths because of processes. Thememory device 3400 a may have channels having widths with improveduniformity through the lower channel LCH and the upper channel UCH thatare formed according to sequential processes.

The second string selection line 3637 and the second ground selectionline 3632 may be arranged above and under the second lower word lines3633 and 3634 and the second upper word lines 3635 and 3636. The secondword lines 3633 to 3636, the second string selection line 3637, and thesecond ground selection line 3632 may be arranged between the first andsecond GIDL selection lines 3631 and 3638.

In an example embodiment, the memory device 3400 a may further includeword lines adjacent to the second string selection line 3637 and dummyword lines adjacent to the second ground selection line 3632. In someembodiments, the memory device 3400 a may further include dummy wordlines arranged on a boundary of the lower channel LCH and the upperchannel UCH.

In the bit line bonding area BLBA, the first cell region CELL1 mayinclude a first through electrode THV1, and the second cell region CELL2may include a second through electrode THV2. The second throughelectrode THV2 may penetrate the second common source line 3620 and theword lines 3633 to 3636. The second through electrode THV2 may include aconductive material. Alternatively, the second through electrode THV2may include a conductive material surrounded by insulation materials.The first through electrode THV1 may include the same material as thesecond through electrode THV2. The first through electrode THV1 and thesecond through electrode THV2 may be electrically connected to eachother through a first through upper metal pattern 3672 b and a secondthrough lower metal pattern 3771 d. The first through upper metalpattern 3672 b may be formed on an upper end of the second upper chipincluding the second cell region CELL2 w, and the second through lowermetal pattern 3771 d may be formed on a lower end of the first upperchip including the first cell region CELL1. The second through electrodeTHV2 may be electrically connected to the third metal layer 3650 c andthe fourth metal layer 3660 c. A first through via 3671 b may be formedbetween the fourth metal layer 3660 c and the first through upper metalpattern 3672 b, and a second through via 3772 d may be formed betweenthe first through electrode THV1 and the second through lower metalpattern 3771 d. The first through upper metal pattern 3672 b and thesecond through lower metal pattern 3771 d may be connected to each otheraccording to the bonding method.

According to an embodiment, a first upper metal pattern 3672 a may beformed on an upper portion of the second cell region CELL2, and a firstlower metal pattern 3771 e may be formed on a lower portion of the firstcell region CELL1. The first upper metal pattern 3672 a of the secondcell region CELL2 and the first lower metal pattern 3771 e of the firstcell region CELL1 may be connected to each other in the external padbonding area PA, according to the bonding method. The second upper metalpattern 3772 a may be formed on an upper portion of the first cellregion CELL1, and the second lower metal pattern 3873 a may be formed onan upper portion of the peripheral circuit region PERI. The second uppermetal pattern 3772 a of the first cell region CELL1 and the second lowermetal pattern 3873 a of the peripheral circuit region PERI may beconnected to each other in the external pad bonding area PA according tothe bonding method. The fourth metal layer 3660 c may be a second bitline.

In an example embodiment, the first cell region CELL1 may include thefirst sub-block SB1 including the memory cells connected to first wordlines 3733 to 3736. The second cell region CELL2 may include the secondsub-block SB2 including the memory cells connected to the second wordlines 3633 to 3636.

In an example embodiment, a direction from the channel of the firstsub-block SB1 to the erase voltage during the erase operation on thefirst sub-block SB1 of the first cell region CELL1 may be different froma direction from the channel of the second sub-block SB2 to the erasevoltage during the erase operation on the second sub-block SB2 of thesecond cell region CELL2. For example, a first bit line 3760C may beselected as the transmission path of the erase voltage during the eraseoperation on the first sub-block SB1, and the channel of the firstsub-block SB1 may be boosted from the first bit line 3760C towards thefirst common source line 3720 because of the erase voltage. The secondcommon source line 3620 may be selected as the transmission path of theerase voltage during the erase operation on the second sub-block SB2,and the channel of the second sub-block SB2 may be boosted by the erasevoltage in a direction from the second common source line 3620 to thesecond bit line 3660 c. As another example, a first common source line3720 may be selected as the transmission path of the erase voltageduring the erase operation on the first sub-block SB1, and the channelof the first sub-block SB1 may be boosted by the erase voltage in adirection from the first common source line 3720 to the first bit line3760 c. The second bit line 3660 c may be selected as the transmissionpath of the erase voltage during the erase operation on the secondsub-block SB2, and the channel of the second sub-block SB2 may beboosted by the erase voltage in a direction from the second bit line3660 c to the second common source line 3620.

However, this is merely an example, and one or more embodiments are notlimited thereto. A direction, in which the channel of the firstsub-block SB1 is boosted by the erase voltage during the erase operationon the first sub-block SB1, may be identical to a direction, in whichthe channel of the second sub-block SB2 may be boosted by the erasevoltage during the erase operation on the second sub-block SB2. Forexample, the first bit line 3760 c may be selected as the transmissionpath of the erase voltage during the erase operation on the firstsub-block SB1, and the second bit line 3660 c may be selected as thetransmission path of the erase voltage during the erase operation on thesecond sub-block SB2. Thus, the above directions may be identical toeach other.

Referring further to FIG. 15B, in an example embodiment, the first cellregion CELL1 may include the first sub-block SB1 including the memorycells connected to the word lines 3733 and 3734 and the second sub-blockSB2 including the memory cells connected to the word lines 3735 and3736. The second cell region CELL2 may include the third sub-block SB3including the memory cells connected to the word lines 3633 and 3634 andthe fourth sub-block SB4 including the memory cells connected to theword lines 3635 and 3636.

In an example embodiment, by considering the positions of the first andsecond sub-blocks SB1 and SB2 in the first cell region CELL1, the firstcommon source line 3720 may be selected as the transmission path of theerase voltage during the erase operation on the first sub-block SB1, andthe first bit line 3760 c may be selected as the transmission path ofthe erase voltage during the erase operation on the second sub-blockSB2. By considering the positions of the third and fourth sub-blocks SB3and SB4 in the second cell region CELL2, the second common source line3620 may be selected as the transmission path of the erase voltageduring the erase operation on the third sub-block SB3, and the secondbit line 3660 c may be selected as the transmission path of the erasevoltage during the erase operation on the fourth sub-block SB4.

Referring further to FIG. 15C, in an example embodiment, the first cellregion CELL1 may include the first sub-block SB1 including the memorycells connected to the word lines 3733 and 3734 and the second sub-blockSB2 including the memory cells connected to the word lines 3735 and3736. The second cell region CELL2 may include the third sub-block SB3including the memory cells connected to the word lines 3633 to 3636.

In an example embodiment, by considering the positions of the first andsecond sub-blocks SB1 and SB2 in the first cell region CELL1, the firstcommon source line 3720 may be selected as the transmission path of theerase voltage during the erase operation on the first sub-block SB1, andthe first bit line 3760 c may be selected as the transmission path ofthe erase voltage during the erase operation on the second sub-blockSB2. During the erase operation on the third sub-block SB3, at least oneof the second bit line 3660 c and the second common source line 3620 maybe selected as the transmission path of the erase voltage.

Referring further to FIG. 15D, in an example embodiment, the first cellregion CELL1 may include the first sub-block SB1 including the memorycells connected to the word lines 3733 to 3736. The second cell regionCELL2 may include the second sub-block SB2 including the memory cellsconnected to the word lines 3633 and 3634 and the third sub-block SB3including the memory cells connected to the word lines 3635 and 3636.

In an example embodiment, during the erase operation on the firstsub-block SB1, at least one of the first bit line 3760 c and the firstcommon source line 3670 may be selected as the transmission path of theerase voltage. By considering the positions of the second and thirdsub-blocks SB2 and SB3 in the second cell region CELL2, the secondcommon source line 3620 may be selected as the transmission path of theerase voltage during the erase operation on the second sub-block SB2,and the second bit line 3660 c may be selected as the transmission pathof the erase voltage during the erase operation on the third sub-blockSB3.

While the inventive concept has been particularly shown and describedwith reference to embodiments thereof, it will be understood thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the following claims.

What is claimed is:
 1. A memory device comprising: a memory blockcomprising a first sub-block and a second sub-block that are connectedbetween a common source line and a plurality of bit lines and verticallystacked; and a control circuit configured to select any one of thecommon source line and the plurality of bit lines as a transmission pathof an erase voltage based on positions of the first sub-block and thesecond sub-block, and perform erase operations on the first sub-blockand the second sub-block in units of sub-blocks, wherein the memoryblock further comprises: a first erase transistor directly connected tothe common source line, and configured to apply the erase voltage to thecommon source line; and a second erase transistor directly connected tothe plurality of bit lines, and configured to apply the erase voltage tothe plurality of bit lines.
 2. The memory device of claim 1, wherein thesecond sub-block is stacked on the first sub-block and closer to theplurality of bit lines than the first sub-block, and wherein the controlcircuit is configured to: select the plurality of bit lines as thetransmission path of the erase voltage in response to the second erasetransistor being turned on, during an erase operation on the secondsub-block, and select the common source line as the transmission path ofthe erase voltage in response to the first erase transistor being turnedon, during an erase operation on the first sub-block.
 3. The memorydevice of claim 2, wherein a channel diameter of the first sub-block isgreater than a channel diameter of the second sub-block at a point atwhich the first sub-block contacts the second sub-block.
 4. The memorydevice of claim 2, wherein the memory block further comprises a thirdsub-block stacked between the first sub-block and the second sub-block,and wherein the control circuit is configured to select any one of thecommon source line and the plurality of bit lines as the transmissionpath of the erase voltage, based on cell types of the first sub-blockand the second sub-block, and perform an erase operation on the thirdsub-block.
 5. The memory device of claim 4, wherein, when the cell typeof the first sub-block has a higher level than the cell type of thesecond sub-block; the control circuit is configured to select theplurality of bit lines as the transmission path of the erase voltageduring the erase operation on the third sub-block, and the second erasetransistor is configured to be turned on such that the erase voltage isapplied to the plurality of bit lines.
 6. The memory device of claim 1,wherein a number of word lines connected to the first sub-block isdifferent from a number of word lines connected to the second sub-block.7. The memory device of claim 1, wherein the memory block furthercomprises: a plurality of first gate induced drain leakage (GIDL)transistors coupled to the common source line; a plurality of groundselection transistors respectively coupled to the plurality of firstGIDL transistors; a plurality of second GIDL transistors respectivelycoupled to the plurality of bit lines; and a plurality of stringselection transistors respectively coupled to the plurality of secondGIDL transistors.
 8. The memory device of claim 7, wherein, when theplurality of bit lines are selected as the transmission path of theerase voltage; the control circuit is configured to control a firstfloating start timing of a plurality of gates of the plurality of secondGIDL transistors and a plurality of gates of the plurality of stringselection transistors to be later than a second floating start timing ofa plurality of gates of the plurality of first GIDL transistors and aplurality of gates of the plurality of ground selection transistors, andthe second erase transistor is configured to be turned on such that theerase voltage is applied to the plurality of bit lines.
 9. The memorydevice of claim 8, wherein the control circuit is configured such thatthe second floating start timing is identical to a timing in which theerase voltage starts to be applied to the plurality of bit lines. 10.The memory device of claim 8, wherein, at a time point, the controlcircuit is configured such that levels of floating voltages of theplurality of gates of the plurality of second GIDL transistors and theplurality of gates of the plurality of string selection transistors arelower than levels of floating voltages of the plurality of gates of theplurality of first GIDL transistors and the plurality of gates of theplurality of ground selection transistors.
 11. A memory devicecomprising: a lower chip comprising a peripheral circuit region; and afirst upper chip stacked on the lower chip, connected to the lower chipaccording to a bonding method, and comprising a first cell region,wherein the first cell region comprises: a first metal layer formedadjacent to the lower chip and connected to a plurality of first bitlines; a first substrate formed at a higher level than the first metallayer and having a lower surface on which a first common source line isformed; and at least two first sub-blocks connected between theplurality of first bit lines and the first common source line andvertically stacked, and wherein the peripheral circuit region comprises:a control circuit configured to: select any one of the plurality offirst bit lines and the first common source line as a transmission pathof an erase voltage based on positions of the at least two firstsub-blocks, and perform an erase operation on the at least two firstsub-blocks; a first erase transistor directly connected to the firstcommon source line, and configured to apply the erase voltage to thefirst common source line; and a second erase transistor directlyconnected to the plurality of first bit lines, and configured to applythe erase voltage to the plurality of first bit lines.
 12. The memorydevice of claim 11, wherein the at least two first sub-blocks arerespectively connected to a plurality of word lines in differentnumbers.
 13. The memory device of claim 11, wherein the at least twofirst sub-blocks comprise: a second sub-block adjacent to the pluralityof first bit lines; and a third sub-block adjacent to the first commonsource line, and wherein the control circuit is configured to: selectthe plurality of first bit lines as the transmission path of the erasevoltage in response to the second erase transistor being turned on,during an erase operation on the second sub-block, and select the firstcommon source line as the transmission path of the erase voltage inresponse to the first erase transistor being turned on, during an eraseoperation on the third sub-block.
 14. The memory device of claim 11,further comprising: a second upper chip stacked on the first upper chip,connected to the first upper chip according to the bonding method, andcomprising a second cell region, wherein the second cell regioncomprises: a second metal layer adjacent to the first upper chip andconnected to a plurality of second bit lines; a second substrate formedat a higher level than the second metal layer and having a lower surfaceon which a second common source line is formed; and at least two secondsub-blocks connected between the plurality of second bit lines and thesecond common source line, and wherein the control circuit is configuredto: select any one of the plurality of second bit lines and the secondcommon source line as the transmission path of the erase voltage basedon positions of the at least two second sub-blocks, and perform an eraseoperation on the at least two second sub-blocks.
 15. The memory deviceof claim 14, wherein the control circuit is further configured tooperate as if the at least two first sub-blocks and the at least twosecond sub-blocks are included in a single memory block.
 16. A memorydevice comprising: a lower chip comprising a peripheral circuit region;and a first upper chip stacked on the lower chip, connected to the lowerchip according to a bonding method, and comprising a first cell region;a second upper chip stacked on the first upper chip, connected to thefirst upper chip according to the bonding method, and comprising asecond cell region, wherein the first cell region comprises: a firstsubstrate adjacent to the second upper chip and having a lower surfaceon which a first common source line is formed; a first metal layeradjacent to the lower chip and connected to a plurality of first bitlines; and a first sub-block comprising a plurality of first memorycells vertically stacked, wherein the second cell region comprises: asecond substrate having a lower surface on which a second common sourceline is formed; a second metal layer adjacent to the first upper chipand connected to a plurality of second bit lines; and a second sub-blockcomprising a plurality of second memory cells vertically stacked, andwherein a direction, in which a channel of the first sub-block isboosted by an erase voltage during an erase operation on the firstsub-block, is different from a direction, in which a channel of thesecond sub-block is boosted by the erase voltage during an eraseoperation on the second sub-block, and wherein the peripheral circuitregion comprises: a first erase transistor directly connected to thesecond common source line, and configured to apply the erase voltage tothe second common source line; and a second erase transistor directlyconnected to the plurality of first bit lines, and configured to applythe erase voltage to the plurality of first bit lines.
 17. The memorydevice of claim 16, wherein the first sub-block is configured to beboosted in the channel of the first sub-block by the erase voltageduring the erase operation on the first sub-block in a direction fromthe plurality of first bit lines to the first common source line, andwherein the second sub-block is configured to be boosted in the channelof the second sub-block by the erase voltage during the erase operationon the second sub-block in a direction from the second common sourceline to the plurality of second bit lines.
 18. The memory device ofclaim 16, wherein the first cell region further comprises a thirdsub-block comprising a plurality of third memory cells verticallystacked, and wherein a direction, in which a channel of the thirdsub-block is boosted by the erase voltage during an erase operation onthe third sub-block, is identical to the direction, which the channel ofthe second sub-block is boosted by the erase voltage during the eraseoperation on the second sub-block.